1. Field of the Invention
The present invention relates generally to an improvement in a control system for an air conditioning compressor of a vehicular air conditioning system, and more particularly to such a control system so configurated as to temporarily disconnect the compressor from an engine in order to improve acceleration performance of the vehicle.
2. Description of the Prior Art
In connection with automotive vehicles equipped with an air conditioning system in which an air conditioning compressor for refregerant is drivably connected to an engine, it has been already proposed and put into practical use to temporarily (for example, 3-10 seconds) disconnect the compressor from the engine when an operation for abrupt acceleration is made, i.e., an accelerator pedal is strongly depressed, so that load to the engine can be reduced during acceleration thereby to improve acceleration performance even a little. This is called an "acceleration cut system" which makes acceleration cut control for disconnecting the compressor from the engine.
In such an acceleration cut system, the rapid vehicle acceleration operation is usually detected, for example, by a pressure responsive switch adapted to be switched ON upon detection of a weakened intake manifold vacuum prevailing during abrupt vehicle acceleration, and an acceleration switch or a kickdown switch adapted to be switched ON when an accelerator pedal is abruptly depressed.
However, difficulties have encountered in automotive vehicles equipped with the above-mentioned acceleration cut system, in which the acceleration cut control is unavoidably frequently made and therefore the frequency of on-off action of the compressor becomes very high, so that the compressor frequently repeats its driven and stop actions. This hastens mechanical exhaustion of the compressor. In this regard, it is desirable to carry out the acceleration cut action of the compressor only when the acceleration cut is really necessary during acceleration. Accordingly, particularly in the automotive vehicles having a sufficient engine power output, frequent acceleration cut actions of the compressor make prominent disadvantage of such compressor mechanical exhaustion relative to advantage of acceleration performance improvement.